1. Field of the Invention
The invention relates to a flash memory device, and more particularly, to a flash memory having two tunnel oxide layers between floating gate and substrate.
2. Description of the Prior Art
A flash memory is a type of non-volatile memory, which can preserve data within the memory even when an external power supply is off. Recently, because flash memories are electrically re-writable and electrically re-erasable, they have been widely applied in the fabrication of electrical products, such as mobile phones, digital cameras, video players, personal digital assistants (PDA) or systems on a chip (SOC).
However, conventional flash memory typically uses a single tunnel oxide layer to carry out programming and erase operations, which not only affects the operation speed of the entire memory cell but also decreases endurance and life expectancy of the device. Hence, how to alter the architecture and operation means of current flash memory thereby improving the endurance of the device has become an important task in this field.